Jun 6, 2013

Upon surfing the net, I have found this site: http://electroschematics.com displaying their projects on making a Transformerless Power Supply with a 12 volts output voltage and a current of 100mA.

This is a transformerless power supply for low current applications. C1 is the X rated AC capacitor that reduces high volt AC. D1-D4 rectifies AC to DC and C2 removes ripples. R1 is the bleeder to remove stored current in AC when power is off. R2 limits inrush current. A Zener can be used in the output to get regulated DC.

Schematic Diagram of Transformerless Power Supply

We usually see this kind of power supply on a China made model of rechargeable products like flashlights and mosquito killer. This circuit catches my attention because of its application in our work which needs a power supply and we can also use this power low current circuits like some of our projects that don’t needs too much power requirements.

Caution! Circuit is lethal since it carries high volt AC. Do not touch or test when connected to Mains. Enclose in a shock proof case.

Note: “Be careful, this circuit is not isolated from 220 volts AC. It needs some extra care in handling this kind of supply. Dangerous High Voltage AC.”